Traditional cigarettes deliver flavor and aroma to the smoker as a result of combustion, during which a mass of tobacco is combusted at temperatures which often exceed 800° C. during a puff. The heat of combustion releases various gaseous combustion products and distillates from the tobacco. As these gaseous products are drawn through the cigarettes, they cool and condense to form an aerosol which provides the tastes and aromas associated with smoking.
Traditional cigarettes produce sidestream smoke during smoldering between puffs. Once lit, they must be fully consumed or be discarded. Relighting a traditional cigarette is possible but is usually not desirable for subjective reasons including flavor, taste, and odor.
An alternative to the more traditional cigarettes includes those in which a combustible material heats a separate bed of tobacco sufficiently to release an aerosol. Such cigarettes may comprise a combustible, carbonaceous heating element (heat source) located at or about one end of the cigarette in a bed of tobacco-laden elements located adjacent the aforementioned heating element. Commonly assigned U.S. Pat. Nos. 5,388,594 and 5,505,214 disclose various heating elements and cigarettes which significantly reduce sidestream smoke while permitting the smoker to selectively suspend and reinitiate smoking.
The aforementioned, U.S. Pat. No. 5,388,594, which is hereby incorporated in its entirety by reference, describes an electrical smoking system including a novel electrically powered lighter and a novel cigarette that cooperates with the lighter. The preferred embodiment of the lighter includes a plurality of metallic serpentine heaters disposed in a configuration that slidingly receives a tobacco rod portion of the cigarette.
The preferred embodiment of the cigarette in U.S. Pat. No. 5,388,594 comprises a tobacco-laden tubular carrier, a cigarette paper overwrapped about the tubular carrier, an arrangement of flow-through filter plugs at a mouthpiece end of the carrier and a filter plug at the free (distal) end of the carrier. The carrier and the lighter are configured such that when the cigarette is inserted into the lighter and as individual heaters are activated for each puff, localized charring occurs at spots about the cigarette in the locality where each heater was bearing against the cigarette (hereinafter referred to as a “heater footprint”). Once all the heaters have been activated, the charred spots are closely spaced from one another and encircle a central portion of the carrier portion of the cigarette.
It is now realized in practice with an electrically heated cigarette smoking system such as that disclosed in U.S. Pat. No. 5,388,594, that non-uniformity of the cigarette circumferences out-of-roundness and deformation of the cigarette when inserted into the lighter may impact performance of electrically heated cigarette smoking system by preventing desired portions of the cigarette from being placed in consistent contact with the various heater elements. Accordingly, it is an object of the present invention to provide a cigarette of an electrical smoking system which has enhanced uniformity in circumference, enhanced roundness and enhanced resistance to deformation.